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.Dd $Mdocdate: June 15 2008 $
.Dt RPC.STATD 8
.Os
.Sh NAME
.Nm rpc.statd
.Nd host status monitoring daemon
.Sh SYNOPSIS
.Nm
.Op Fl d
.Sh DESCRIPTION
.Nm
is a daemon which co-operates with rpc.statd daemons on other hosts to provide
a status monitoring service.
The daemon accepts requests from
programs running on the local host (typically,
.Xr rpc.lockd 8 ,
the NFS file locking daemon) to monitor the status of specified hosts.
If a monitored host crashes and restarts, the remote daemon will
notify the local daemon, which in turn will notify the local program(s)
which requested the monitoring service.
Conversely if this host crashes and restarts when
.Nm
restarts, it will notify all of the hosts which were being monitored
at the time of the crash.
.Pp
The options available are:
.Bl -tag -width Ds
.It Fl d
Causes debugging information to be written to
.Xr syslog 3 ,
recording all RPC transactions to the daemon.
These messages are logged with level
.Dv LOG_DEBUG
and facility
.Dv LOG_DAEMON .
Error conditions are logged irrespective of this option, using level
.Dv LOG_ERR .
.El
.Pp
The
.Nm
daemon must NOT be invoked by
.Xr inetd 8
because the protocol assumes that the daemon will run from system start time.
Instead, it should be configured in
.Xr rc.conf 8
to run at system startup.
.Sh FILES
.Bl -tag -width /usr/include/rpcsvc/sm_inter.x -compact
.It Pa /usr/include/rpcsvc/sm_inter.x
RPC protocol specification used by local applications
to register monitoring requests.
.It Pa /var/db/statd.status
Non-volatile record of currently monitored hosts.
.El
.Sh SEE ALSO
.Xr syslog 3 ,
.Xr rc.conf 8 ,
.Xr rpc.lockd 8
.Sh STANDARDS
This implementation is based on the specification in
the X/Open CAE Specification C218,
"Protocols for X/Open PC Interworking: XNFS, Issue 4",
ISBN 1 872630 66 9.
.Sh HISTORY
A version of
.Nm
appeared in
.Tn SunOS 4 .
.Sh BUGS
There is no means for the daemon to tell when a monitored host has
disappeared permanently (e.g. catastrophic hardware failure), as opposed
to transient failure of the host or an intermediate router.
At present,
it will retry notification attempts at frequent intervals for 10 minutes,
then hourly, and finally gives up after 24 hours.
.Pp
The protocol requires that symmetric monitor requests are made to both
the local and remote daemon in order to establish a monitored relationship.
This is convenient for the NFS locking protocol, but probably reduces the
usefulness of the monitoring system for other applications.
.Pp
The current implementation uses more than 1Kbyte per monitored host in
the status file (and also in VM).
This may be inefficient for NFS servers
with large numbers of clients.
